Liquid additive slow-release apparatus driven by a filter pressure gradient

ABSTRACT

The present invention provides a filter assembly containing a filter element and a container as a depot for a liquid additive. The container can include an inlet and an outlet, which are configured to allow a liquid to flow into the container mix with the contained additive and then flow out into the system. It has been observed that a liquid flowing through a filter assembly exhibits a pressure gradient within the filter. Consequently, the inlets and outlets to the container can be positioned to take advantage of the pressure gradient to enhance the addition of the additive to the liquid in the filter assembly.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a CIP of, and claims the benefit of U.S.application Ser. No. 10/767,513 filed on Jan. 29, 2004, which is herebyincorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

The present invention is directed to a liquid filtration system and to amethod of treating the liquid in the enclosed system.

Filter assemblies are commonly used to protect combustion engines byfiltering out contaminants and thereby preventing damage to the engineand other downstream components such as valves, fuel injectors, fuellines, and related other components. To maintain engine performance andreliability, the filter assemblies must be replaced, often as frequentlyas every 2,000 to 4,000 vehicle miles.

It can be equally important to add agents to the fuel to reduce damageto the engine and related downstream components and/or to enhance theperformance of the engine. For example, since the early 1990's dieselfuel producers have significantly reduced the sulfur content in dieselfuel to reduce the environmental harm that was attributed to the burningof high sulfur content fuels. However, the naturally occurring sulfur inthe diesel fuel also acted as a lubricant. The resulting low sulfurcontent diesel fuel caused increased wear on the diesel engine and, inparticular, to the fuel pump and injectors, which in turn causedsignificant harm to the overall operation, performance, and efficiencyof the engine and even to the environment. Consequently, variousadditives were developed to increase not only the lubricity but also toenhance fuel stability, fuel combustion, and engine performance.

It is difficult to maintain a constant or desired level of the additivein the fuel. Typically an operator adds a bottled additive or additiveconcentrate to the vehicle fuel tank with each fuel fill-up. While manybottled fuel additives are commercially available, often operators donot consistently add the additive with each fill-up—the additive mightnot be readily available or the operator may forget to include theadditive. Combining the additive with fuel in the fuel tank may notreliably provide a homogenous fuel/additive mixture.

Fuel tanks do not include reliable methods for mixing fuel. Generallyoperators rely upon the turbulence created during a fill-up and byvehicle motion to mix the additive and fuel. Furthermore, the additiveconcentration in the fuel may vary, depending upon the amount of fuel inthe fuel tank—assuming a set amount of additive is added with eachfill-up.

Various alternative methods have been developed to add the additives tofuel. One method includes providing a fuel additive in a filter assemblysuch as disclosed in U.S. Pat. No. 6,238,554 issued to Martin et al.,which adds the additive to the fuel under diffusion-controlledconditions.

Another method is disclosed by Davis in U.S. Pat. No. 5,507,942, whichincludes a filter assembly with a solid fuel additive that dissolves inthe fuel as the additive contacts the fuel in the filter assembly.

The present invention provides a novel method of treating fuel bycapitalizing on the existence of or developing a fluid pressure gradientwithin the filter assembly. The pressure gradient can then be harnessedto continuously add the fuel additive to the fuel flowing through thefilter assembly. Consequently, the present invention provides noveladvancements and additionally provides a wide variety of benefits andadvantages in the relevant subject matter.

While the above discussion has been directed toward filter assemblies,the present invention provides a novel filter assembly and method oftreating the fluid flowing through that filter, regardless of whetherthat liquid is a fuel. The principles embodied in the present inventionapply to filters in general and can be used in filter assemblies,hydraulic filters, lubricant filters, and/or coolant filters.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to a novel filter assembly, themanufacture and use thereof. Various aspects of the invention are novel,nonobvious, and provide various advantages. While the actual nature ofthe invention covered herein can only be determined with reference tothe claims appended hereto, certain forms and features, which arecharacteristic of the preferred embodiments disclosed herein, aredescribed briefly as follows.

In one form, the present invention provides a filter assembly thatcomprises a housing defining an interior chamber and including an inlet,an outlet, and a fluid pathway for a liquid flowing through the interiorchamber. Liquid flowing through the fluid pathway generates a pressuregradient within the interior chamber such that in a first region of theinterior chamber, the flowing liquid exhibits a first (higher) fluiddynamic pressure and in a second region the flowing liquid exhibits asecond (lower) fluid dynamic pressure. The filter assembly also includesa filter element disposed in the interior chamber in the fluid pathwaybetween the inlet and the outlet and a container disposed within theinterior chamber. The container has an exterior wall that defines aninterior region. The container also includes a first opening with afirst capillary tube extending from the exterior wall and a secondopening through the exterior wall and spaced apart from the firstopening. The first opening and said second opening each provide fluidcommunication between the interior chamber and the interior region. Aliquid additive can be deposited in the interior region. The liquidadditive can be selected to provide a benefit to at least one of a fuel,oil, lubricant, and coolant.

In another form, the present invention provides a filter assembly thatcomprises a housing defining an interior chamber and including an inletand an outlet into the interior chamber; and a filter element disposedin the interior chamber between the inlet and the outlet. The filterelement partitions the interior chamber into two regions—an enteringregion proximate to the inlet and an exiting region proximate to theoutlet. The filter assembly also includes a container disposed withinthe interior chamber that defines an interior region. The container hasa first capillary tube extending into the entering region and a secondcapillary tube providing fluid communication between the interior regionand the interior chamber. A liquid additive, which has been selected toprovide a benefit to the liquid flowing through the filter, can bedeposited in the interior region of the container.

In other forms, the present invention provides a filter assembly thatcomprises a housing defining an interior chamber; a filter elementdisposed within the housing and that partitions the interior chamberinto an inlet region and a filtered region. The container is positionedwithin the housing and defines a reservoir. The container includes afirst opening that allows the fluid from the inlet region into thereservoir and a second opening allowing the additive or a mixture of theadditive and the fluid to flow out of the reservoir toward the outlet tothe assembly.

In other forms, the present invention provides a filter assembly forfiltering a fluid. The filter comprises a housing defining an interiorchamber, the housing including a nut plate having an inlet and an outletfor the fluid. The filter also includes a filter element that ispermeable to the fluid and which is disposed within the housing; and acontainer that is also positioned within the housing. The containerdefines a reservoir configured for receipt of a liquid additive. Thecontainer also includes a first opening allowing fluid entering from theinlet to flow into the reservoir and a second opening allowing a liquidadditive deposited within the reservoir to flow toward the outlet. Thefirst opening and the second opening are configured to allow fluid toflow through the container at a fluid face velocity (and hencecorresponding pressure drop) therethrough) of about less than 50% of thefluid face velocity of the primary flow through the filter element.

In still other forms, the present invention provides a filter assemblyfor filtering a fluid. The filter comprising: a housing defining aninterior chamber, the housing including a nut plate having an inlet andan outlet for the fluid; a filter element permeable to the fluid anddisposed within the housing; and a container positioned within thehousing. The container defines a reservoir configured for receipt of aliquid additive and can further include a first opening allowing fluidentering from the inlet to flow into the reservoir and a second openingallowing a liquid additive deposited within the reservoir to flow to theoutlet. The second opening is constricted relative to the first openingto attenuate the fluid flow into the container.

In still yet other forms the present invention provides a method ofreleasing an additive into a fluid flowing through a filter assembly.The method comprises: configuring a filter assembly with an inlet, anoutlet, and a fluid pathway therebetween through which the fluid canflow; creating a fluid pressure differential along the fluid pathwaybetween the inlet and the outlet; and positioning a reservoir with afirst opening and a second opening in fluid communication with the fluidpathway whereby the pressure differential induces an additive disposedwithin the reservoir to be released into the fluid.

The present invention also provides a method of supplying an additive tothe liquid flowing through a filter assembly. The method comprisesgenerating a dynamic fluid pressure gradient within the filter housing;providing an additive in a container within the filter housing;positioning an inlet port for the container proximate to an area of afirst dynamic fluid pressure within the filter housing; and positioningan outlet port for the container proximate to an area of a seconddynamic fluid pressure less than the first dynamic fluid pressurethereby inducing the liquid additive to flow out of the container.

Further features, aspects, forms, advantages, and benefits shall becomeapparent from the description and drawings contained herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of one embodiment of a filter assemblyin accordance with the present invention.

FIG. 2 is an exploded cross-sectional view of a filter of the filterassembly of FIG. 1.

FIG. 3 is a partial view in full section of the lower portion of thefilter illustrated in FIG. 1.

FIG. 4 is a graph illustrating the dynamic pressure of a fluid flowingthrough a filter measured at varying axial position within the filterhousing between the filter and shell.

FIG. 5 is a graph comparing the flowrate of a fluid entering a containerwith a capillary tube outlet to a container without a capillary tubeoutlet.

FIG. 6 is a graph comparing the flowrate of a liquid additive (theactive ingredient portion of an increasingly dilute mixture) exiting acontainer with a capillary outlet to a container without a capillaryoutlet.

FIG. 7 is a partial view in full section of an alternative embodiment ofa filter assembly in accordance with the present invention.

FIG. 8 is a partial view with sections broken away of yet anotheralternative embodiment of a filter assembly with a flow-directing insertin accordance with the present invention.

FIG. 9 is a sectional view taken along section line 9—9 of theflow-directing insert illustrated in FIG. 8.

FIG. 10 is a cross-section view of another embodiment of the filterassembly in accordance with the present invention.

FIG. 11 is a sectional view taken along section line 11—11 of theadditive cartridge illustrated in FIG. 10.

FIG. 12 is a perspective view of a replaceable cartridge for use in thepresent invention.

FIG. 13 is a cross-sectional view of the replaceable cartridgeillustrated in FIG. 12.

FIG. 14 is an elevated view in full section of yet another embodiment ofa filter assembly with a replaceable cartridge in accordance with thepresent invention.

FIG. 15 is a cross-sectional view of still yet another embodiment of afilter assembly with an extended shroud on the filter element endcap forenhanced liquid velocity at the inlet tube in accordance with thepresent invention.

FIG. 16 is a partial view of the extended shroud on the filter elementendcap and inlet tube illustrated in FIG. 15.

FIG. 17 is a cross-sectional view of yet another embodiment of a filterassembly in accordance with the present invention.

FIG. 18 is a cross-sectional view of an additive cartridge for use inthe filter assembly of FIG. 17.

FIG. 19 is a perspective view of the additive cartridge of FIG. 17.

FIG. 20 is a partial cross-sectional view of an alternative embodimentof the upper lid for a cartridge for use in the filter assembly of FIG.17.

FIG. 21 is a perspective view of the additive cartridge illustrating thelower wall portion in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustratedherein, and specific language will be used to describe the same. It willnevertheless be understood that no limitation of the scope of theinvention is thereby intended. Any alterations and further modificationsof the described filters, cartridges, and processes, and any furtherapplications of the principles of the invention as described herein, arecontemplated as would normally occur to one skilled in the art to whichthe invention relates.

FIG. 1 is a cross-sectional view of a filter assembly 10 provided inaccordance with the present invention. FIG. 2 is an exploded,cross-sectional view of the same filter assembly 10. Filter assembly 10includes a housing or outer casing 12 defining an interior chamber 14. Anut plate 16 is secured across an open end 13 of casing 12. Nut plate 16provides at least one inlet 18, preferably a plurality of inlets, and atleast one outlet 20. In the illustrated embodiment, nut plate 16includes a plurality of inlets 18 encircling a centrally-located outlet20. Both inlet(s) 18 and outlet 20 provide fluid communication withinterior chamber 14 to allow a liquid such as, and organic based fuel,lubricant, or oil fluid; or an aqueous based coolant, to flow into andout of interior chamber 14. Additionally, a filter element 22 and avessel or container 24 and, optionally, biasing element 26, are providedin interior chamber 14.

Filter element 22 is positioned in a fluid pathway between the liquidentering through inlet 18 and exiting through outlet 20. Additionally,filter element 22 can partition interior chamber 14 into a liquidentering region 28 and a liquid exiting region 30. Filter element 22 isprovided in the form of any known and commercially available filtermaterial. Examples of a material that can be used as a filter elementinclude paper (cellulose), cloth, polyester, wire mesh, plastic mesh,gradient density melt-blown polymeric materials, and the like. In theillustrated embodiment, filter element 22 is provided as a cylindricalsleeve formed of a pleated sheet of filter material. The cylindricalsleeve defines a centrally-located axis 23. On either end of thecylindrical sleeve, filter element 22 is supported within interiorchamber 14 with a first and second filter endcaps 31 and 32 to provide afluid-tight seal. Consequently, a liquid flowing through filter assembly10 must pass through filter 22 to flow from entering region 28 toexiting region 30.

Filter assembly 10 can also includes a water in fuel sensor and/or drainvalve 35 in outer casing 12. It will be understood that for someapplications the filter assembly need not include a drain valve.However, when present, drain valve 35 can be used to drain out any waterthat has separated from a non-aqueous liquid such as the organic basedfuels, oils, and lubricants. The separated water can collect in thebottom of the interior chamber 14. The water droplets can flow downbetween the inside wall of casing 12 and the exterior wall of container24, which can have vertically extending spacers 37 to separate andcentrally position container 24 in the interior chamber 14.

Referring additionally to FIG. 3, which is a partial view in fullsection of the lower portion of filter assembly 10, container 24, FIGS.1, 2, is positioned inside interior chamber 14. A liquid additive 25 canbe deposited in the interior chamber 14. In the illustrated embodiment,container 24 is disposed between the closed end 27 of outer casing 12and the lower endcap 32 of filter element 22. Biasing element 26, whichis illustrated as a circular spring, biases container 24 against thelower endcaps 32 of filter element 22, and, consequently, forces endcap31 of filter element 22 against nut plate 16 or a seal disposedtherebetween.

Container 24 includes an exterior wall 34. In the illustratedembodiment, exterior wall 34 includes a plurality of spacers 37 eachconfigured as a small, axially-oriented rib. The spacers 37 provide agap between the exterior wall 34 of container 24 and the interior wallof casing 12 so that separated water can fall down between the wall 34where a drain valve 35 can be used to remove the accumulated water.Exterior wall 34 defines an interior region 40. In this embodiment,container 24 defines a cylindrical reservoir or depot concentric aboutaxis 23. Container 24 can be provided as a two-piece (or more)structure(s), which pieces are interconnected via a connection. Theconnection can be a threaded connection sealed with adhesive, snap-fit,ultra-sonic welded, or spin-welded, as desired. In a preferredembodiment, container 24 will be provided as a two-piece structure witha spin-weld connection joining the two structures.

Entrance port 42 provides an opening through exterior wall 34.Similarly, exit port 44 also provides an opening through wall 34. Bothentrance port 42 and exit port 44 provide a pathway for liquid ininterior chamber 14 to enter and exit, respectively, interior region 40of container 24. Preferably both entrance port 42 and exit port 44 arelocated in a top wall portion 41 of container 24.

In a preferred embodiment, entrance port 42 is provided as a smalldiameter tube or capillary tube 48. In a particularly preferredembodiment, capillary tube 48 has a desired length to extend intointerior chamber 14 and adjacent to filter element 22. In thisembodiment, capillary tube 48 provides a fluid conduit for liquid inentering region 28 to flow into interior region 40. Preferably thelength and/or diameter of capillary tube 48 is selected to takeadvantage of the fluid pressure generated by the liquid flowing throughfilter assembly 10 and to induce a portion of the liquid to enterinterior region 40 at a desired flowrate.

In one embodiment, capillary tube 48 extends from container 24 towardsinlet 18 between casing 12 and filter element 22. In one preferredembodiment, capillary tube 48 extends the length of filter element 22.In other embodiments, the length of capillary tube 48 that extendsbeyond the exterior of container 24 is selected to be less than or equalto about three-fourths of the length of the filter element; or thelength of capillary tube 48 is selected to be less than or equal toabout one-half of the length of the filter element; still yet in anotherembodiment the length of capillary tube 48 is selected to be less thanor equal to about one-fourth of the length of the filter element. Thecapillary tube end 49 can be provided in a variety of configurationsincluding a round, oval, flattened configuration, or it can beconfigured to conform to the space between the exterior of the filterelement and the interior of the housing.

Opposite end of capillary tube 48 can also extend into interior region40. In the illustrated embodiment, capillary tube 48 extends adjacent tothe lower wall portion or bottom of container 24. Tube 48 can extend adesired distance inside container 24 from the top wall portion 41 to thebottom wall portion 51. In one embodiment, this distance is greater thanabout one half the distance between wall portions 41 and 51, in otherembodiments this distance is greater than about three fourths thatdistance. This prevents the incoming liquid from flowing directly acrossthe top of container 24 toward exit port 44. It is preferable that theincoming liquid mix sufficiently with the additive contained withincontainer 24. One method of promoting adequate mixing of the liquid andadditive is to increase the period of time that the liquid remains incontainer 24 and/or increase the distance that the incoming liquid mustflow in the interior region before exiting out exit port 44. It will beunderstood that in alternative embodiments capillary tube 48 need notextend to the bottom of container 24.

In the preferred embodiment, the difference in liquid density and theadditive density can be utilized to achieve a more uniform release rateover time. Generally, the liquid additive is denser than the liquidflowing through the filter assembly (regardless whether the liquid isorganic or aqueous based). Consequently, the filtered liquid tends to“float” on the additive phase. Truncating the inlet tube near the top ofthe additive vessel, and extending the outlet capillary near the bottomof the vessel takes advantage of this property. During operation, theliquid enters the inlet vessel, floats, and remains (largely, withexception of the slow diffusion between phases) at the top of the vesselor layered on the liquid additive. As more of the liquid enters throughthe inlet vessel, the entering liquid displaces pure additive andpushing it out the outlet tube in nearly full-concentration yielding avery steady injection of active ingredient into the system.

Exit port 44 is provided in an upper wall portion of exterior wall 34and is spaced apart from entrance port 42. Furthermore, in theillustrated embodiment, exit port 44 is centrally positioned in exteriorwall 34 to extend centrally into interior region 40. However, it will beunderstood that exit port 44 can be positioned as desired in exteriorwall 34 to extend into and/or through any portion of container 24. Asillustrated in FIG. 1, exit port 44 can be defined by a capillary tube54 extending into interior region 40. Capillary tube 54 provides aconduit between interior region 40 and interior chamber 14.

In one embodiment, capillary tube 54 provides fluid communicationbetween the liquid and an additive initially located in interior region40 and entering region 28. From entering region 28, liquid can then flowthrough filter element 22 and into exiting region 30. From there, theliquid can then flow through outlet 20 and back into the system—either arecirculating fuel, coolant, oil, or lubricant system or a single-passfuel system.

In an alternative embodiment, capillary tube 54 provides an exit for theliquid and additive in interior region 40 to flow to exiting region 30.In this embodiment, capillary tube 54 provides direct fluidcommunication for a liquid and/or an additive mixture in interior region40 and exiting region 30 and, ultimately, to outlet 20. Consequently, inthis embodiment, the liquid and additive in interior region 40 canbypass filter element 22. This embodiment would offer a high gradientpressure, since the restriction of the filter element is now added tothe dynamic pressure gradient (Pdyn). This embodiment can provideparticular advantages, for example, for injecting a very viscousadditive into the system. If desired, a small filter medium, such as asintered porous plug, wire-mesh screen, or the like, can be included onthe outlet tube to prevent any large particles that have bypassed thefilter from causing damage to downstream components. The filter mediumcan be located on either end of the outlet tube.

Optionally, entrance port 42 and/or exit port 44 can be sealed with asoluble seal 43 and 45, respectively. This allows filter assembly 10 tobe storage stable, and in particular, this can inhibit loss of activityand/or volume of the additive in container 24. In use, a liquid flowingthrough filter assembly 10 dissolves the seal material, allowing theliquid to enter into interior region 40 and mix with the additivetherein. Alternatively, the soluble seal can be composed of a lowmelting material that melts when exposed to the normal operatingtemperatures of the fuel flowing through the filter.

In one embodiment when the liquid is an organic base fluid such as fuel,oil or a lubricant, the soluble seal is composed of a material such as awax that is soluble in organic solvents.

Optionally, a separate, second container illustrated as pre-chargereservoir 56 can be included in filter assembly 10. In the illustratedembodiment, pre-charge reservoir 56 is positioned in or on container 24.Pre-charge reservoir 56 is separated from the interior region 40 (andthe liquid additive 25 therein) by partition 57 which can be the upperwall portion of container 24. One end 58 of reservoir 56 can be open oralternatively end 58 can be covered with a mesh or other porousstructure. An additive 59 can be deposited into pre-charge reservoir 56and made available for immediate release into the liquid flowing throughfilter assembly 10. Additive 59 can be the same or different fromadditive 25. In a preferred embodiment, the additive 59 in thepre-charge reservoir is a solid or semi-solid material that dispenses ordisperses into the liquid flowing through the filter assembly.

The liquid additive 25 can be selected from any known and commerciallyuseful composition that can provide beneficial properties to theparticular liquid being filtered. The additive can be a liquid atambient temperature or a solid component that has been dissolved in asuitable solvent. Examples of suitable fuel additives for use in thepresent invention include but are not restricted to lubricity aids,ignition promoters, and the like. Specific examples of lubricity aidsinclude: alcohols, monohydroxy alkanols such as saturated aliphaticmonohydric alcohols having from 1 to 5 carbon atoms, methanol, ethanol,propanol, n-butanol, isobutanol, amyl alcohol and isoamyl alcohol;monocarboxylic acids either saturated or unsaturated fatty acids, suchas, caprylic acid, pelargonic acid, capric acid, undecylic acid, lauricacid, tridecoic acid, myristic acid, stearic acid, linoleic acidhypogeic acid, oleic acid, elaidic acid, erucic acid, brassidic acid;organo nitrates, such as, methyl nitrate ethyl nitrate, n-propylnitrate, isopropyl nitrate, allyl nitrate, n-butyl nitrate, ,isobutylnitrate, sec-butyl nitrate, tert-butyl nitrate, n-amyl nitrate, isoamylnitrate, 2-amyl nitrate, 3-amyl nitrate, tert-amyl nitrate, n-hexylnitrate, 2-ethylhexyl nitrate, n-heptyl nitrate, sec-heptyl nitrate,n-octyl nitrate, sec-octyl nitrate, n-nonyl nitrate, n-decyl nitrate,cyclopentylnitrate, cyclohexylnitrate, methylcyclohexyl nitrate,isopropylcyclohexyl nitrate and the like. Examples of these fueladditives can be found in U.S. Pat. Nos. 4,248,182, 5,484,462,5,490,864, and 6,051,039, each of which is incorporated herein byreference in its entirety. Furthermore, it should be understood that theterm “fuel” as used herein includes diesel, biodiesel, gasoline,kerosene, alcohol, or other petroleum distillates. Consequently, theadditive can be selected to provide a benefit to any of these differentfuel compositions.

Additionally, the filter assemblies as described herein can be used withfuel delivery systems for combustion engines, including both diesel andgasoline engines, and/or for any other fuel storage and delivery deviceor system which may or may not be directly connected to a combustionengine.

The additives for coolants, lubricants, hydraulic fluids, and oil canalso be included in either the interior region 40 and/or the pre-chargereservoir 56.

Examples of aqueous coolant additives that can be used in the presentinvention include one of more of the following without limitation:anticorrosion additives such as neutralized dicarboxylic acids,mercaptobenzothiazole, benzotriazole, tolyltriazole, and salts ofmolybdate, nitrite, nitrate, and silicate (preferably with ammonium,tetraalkyl ammonium, or alkali metal as the counter ion); and bufferingagents which can be selected from any known or commonly used bufferingagents, such as, borate salts and phosphate salts; as well as a varietyof other additives, including defoamers, scale inhibitors, surfactants,detergents, and dyes. Examples of defoamers include components (alone orin combination) such as silicon defoamers, alcohols such aspolyethoxylated glycol, polypropoxylated glycol or acetylenic glycols.Examples of scale inhibitors include components, either alone or incombination, such as, for example, phosphate esters, phosphinocarboxylate, polyacrylates, polymethacylate, styrene-maleic anhydride,sulfonates, maleic anhydride co-polymer, acrylate-sulfonate co-polymerand the like. Surfactants for use in this invention include, forexample, either alone or in combination alkyl sulfonates, acrylsulfonates, phosphate esters, sulfosuccinate, acetylenic glycol, andethoxylated alcohols. Detergents include non-ionic and/or anioniccomponents such as, for example, phosphate ester surfactants, sodiumalkyl sulfonates, sodium aryl sulfonates, sodium alkyl aryl sulfonates,linear alkyl benzene sulfonates, alkylphenols, ethoxylated alcohols,carboxylic esters, and the like. Examples of the coolant additives arediscussed in U.S. Pat. No. 4,717,495, published US patent application20030042208, and pending U.S. patent applications Ser. Nos. 09/611,332and 09/611,413 both filed on Jul. 6, 2000, all of which are herebyincorporated by reference.

Additives for lubricants and oils are discussed in WO 03/018163, whichis incorporated by reference herein. Examples include, but are notlimited to, one or more viscosity index improvers, antioxidants (alsoknown as oxidation inhibitors), antiwear agents; and detergents.Specific examples include: detergents, such as, sodium, barium, calciumor magnesium salts of salicylate esters, sulfonates, phosphonates,phenates, thiophosphonates; alkoxides, or carboxylates; dispersants,such as, long-chain and/or high molecular-weight ashless organicmolecules, such as N substituted alkenyl succinimides, esters andpolyesters, amine and polyamine salts of organic acids, Mannich basesderived from alkylated phenols, copolymers of methacrylates oracrylates, ethylene, propylene copolymers containing polar groups orvinyl acetate fumaric acid ester copolymers; antioxidants, such as, zincdialkyl or diaryl dithiophosphates, phenolic compounds, organicphosphites, metal dithiocarbamates, sulfurized olefins, hindered oraromatic amines, organic selenides, phosphorized or sulfurized terpenes;corrosion inhibitors, such as, zinc dithiophosphates, organicphosphates, metal dithiocarbamates, phosphorized or sulfurized terpenes,sulfurized olefins, aromatic nitrogen compounds, sulfonates, alkenylsuccinic acids, propoxylated or ethoxylated alkyl phenols, substitutedimidazoles, barium, calcium or magnesium salts of oxides or carbonates;antiwear additives, such as, zinc, calcium, magnesium, nickel, cadmiumor tetralkyl ammonium salts of dithiophosphoric, various molybdenumsulfur compounds, organic phosphites, sulfurized olefins, varioustriazoles, fatty acid derivatives, dicarbamate derivatives, and alkalinecompounds as acid neutralizers; viscosity index improvers, such as, highmolecular-weight polymers, for example olefin copolymers,ethylene-propylene copolymers, and polyisobutylenes, various styrenecopolymers, for example, styrene and butadiene or isoprene; pour pointdepressants, such as, alkylated naphthalene, polymethacrylates,crosslinked alkylated phenols, vinyl acetate, fumaric acid estercopolymers, alkyl fumarate, vinyl ester copolymers, styrene-estercopolymers, derivatized alkyl methacrylate/acrylate copolymers, olefincopolymers, alkylated polystyrene; anitfoamants, such as, silicones,polyethers; emulsifiers, such as, metal salts of carboxylic acids toname a few examples.

In use, the liquid to be filtered flows in through one or more of inlets18 in nut plate 16, and from there into interior chamber 14. In theillustrated embodiment, a liquid flows into entering region 28 in thedirection indicated by inflow arrows 60. It has been observed that theliquid flowing through a filter such as filter assembly 10 illustratedin FIGS. 1 through 3 exhibits a dynamic fluid pressure gradient withinthe interior chamber.

FIG. 4 is a graph illustrating the dynamic fluid pressure predicted by acomputational fluid dynamics (CFD) model at varying axial positionswithin a filter [all points taken at radial position midway in gapbetween filter shell ID (12) filter element pleat OD (22)]. The graphindicates that the fluid dynamic pressure is greatest near the top ofthe filter element endcap 31 where the axial velocity is highest. Thedynamic pressure below the top endcap begins to diminish since the axialvelocity decreases as fluid is carried inward through the filter. They-axis on the graph is the CFD-predicted dynamic fluid pressure, in Kpa.The x-axis corresponds to the axial position in the filter measured withrespect to the filter element at which the dynamic fluid pressure wasreported via CFD. In the graph illustrated in FIG. 4, the bottom endcapof the filter element is at 0.1 m and the top is at ˜0.225 m. Theabsolute value of the dynamic fluid pressure within the filter can varydepending upon a variety of factors that affect flow velocity in the gapbetween filter and housing, including: the overall length of the filterhousing and/or filter element, the size of gap (annulus area) betweenthe filter element and housing shell, the overall length of the filterhousing and/or filter element, the configuration of the filter element(number of pleats, outer diameter of pleats, inner diameter of pleats,media thickness), the flowrate or volume of flowing liquid through thefilter casing and/or filter element, and the density of the flowingliquid. The dynamic pressure, Pdyn, can be calculated according toEquation 1:Pdyn=1/2×density×velocity²  (1)where density is the liquid density and velocity is the velocity of theliquid flowing through the filter.

The present invention takes advantage of this observation by positioningentrance port 42 where Pdyn is at a relatively high pressure andlocating exit port 44 in an area within the interior chamber thatexhibits lower fluid pressure. Since the entrance port is alignedperpendicular with the direction of flow (like a pitot tube), astagnation zone forms in front of the tube causing the dynamic pressureto be converted to a static pressure which is harnessed to drive flowslowly into the tube and through the vessel.

In the illustrated embodiment, entrance port 42 is defined by the openterminal end of capillary tube 48. Capillary tube 48 extends frominterior region 40 through wall 34 and up between filter element 22 andthe interior wall of outer casing 12. Placing the entrance port 42 atthe terminus of capillary tube 48 in an area of relatively high fluidpressure induces the liquid flowing through the liquid filter to enterinterior region 40. In interior region 40, the liquid can mix with theliquid additive. Thereafter, the liquid and additive mixture can exitthrough exit port 44.

In one embodiment, exit port 44, as noted above, allows the liquid andadditive mixture to re-enter the entering region 28 albeit in an areawhere the dynamic fluid pressure is less than the pressure in the areaadjacent entrance 42 to capillary tube 48. In this embodiment, theliquid and additive mixture from the interior region 40 flows throughthe filter element 22 before exiting the filter assembly through outlet20.

In an alternative embodiment, exit port 44 provides direct fluidcommunication between interior region 40 and exiting region 30. Thisallows the liquid and additive mixture from the interior region 40 toexit into exiting region 30 and from there be mixed with the bulk liquidin exiting region 30 into the fuel conduit (not shown) without passingthrough filter element 22. In this embodiment, as noted above, aseparate filter element can be included with exit port 44, if desired.

Providing entrance port 42 in an area of relatively high fluid pressureand positioning exit port 44 in an area of lower fluid pressure providessubstantial benefits for adding additives to flowing liquid. The releaserate of a liquid additive in container 24 can be tailored as described.In one preferred embodiment, the desired release rate remains relativelyconstant over a long time period. This effect can be modified by varyingthe initial viscosity of the liquid additive in container 24. Forexample, if the initial viscosity of the liquid additive issubstantially higher than that of the liquid flowing through filterassembly 10, then as the liquid begins to mix with and dilute theadditive in the interior of container 24, the initial viscosity of theliquid and additive mixture slowly begins to decrease. The highviscosity inhibits rapid initial release of additive from container 24due to the controlling restriction provided by the outlet capillarytube. The inlet capillary tube may also have a restriction, but sincethe liquid viscosity is much lower than that of the additive and theinlet tube is filled only with the liquid, the outlet capillaryrestriction largely controls/sets the flowrate that results from thefixed gradient pressure. However, over time, the relative amount ofliquid in the liquid and additive mixture in container 24 increases. Asthe relative amount of the liquid component in the liquid and additivemixture increases, the viscosity of the resulting liquid and additivemixture decreases. The resulting decrease in viscosity causes the outletcapillary tube restriction to decrease which leads to correspondingincrease in flowrate (of diluted fuel/additive mix), hence giving a morestable release of actual active ingredient (additive). At a givenpressure gradient, the flowrate through the additive vessel having twocapillary tubes in series (an inlet and an outlet) with differingviscosity in each tube (and neglecting any contribution of viscous dragoffered by the vessel) can be modeled according to the followingEquation 2:

$\begin{matrix}{Q = \frac{P\;\pi\; D_{2}^{4}D_{1}^{4}}{128( {{\mu_{2}L_{2}D_{2}^{4}} + {\mu_{1}L_{1}D_{1}^{4}}} )}} & (2)\end{matrix}$where Q=flowrate, P=gradient pressure, D₁=inlet tube diameter, D₂=outlettube diameter, μ₂=additive viscosity, L₂=outlet tube length, L₁=inlettube length, and μ₁=liquid viscosity. According to Equation 2, thedesired flowrate can be easily adjusted by varying the tubegeometries—especially the tube diameters, D₁ and D_(2,) since flowvaries inversely with the tube diameters to the fourth power. In use,the additive viscosity μ₂ will slowly decrease and the flowrate willincrease. This effect will be more pronounced if the outlet tubeprovides the largest restriction to flow, for example, if D₁ were small.It has been determined that it is typical to achieve a ˜three-foldincrease in flow over the life of the filter/additive vessel whenworking with a ten-fold additive/fuel viscosity ratio. This three-foldincrease in flow helps to counteract the decreasing active ingredientrelease rate due to the exponentially decaying concentration of activeingredient in the vessel.

FIGS. 5 and 6 are graphs which illustrate this effect for two caseswhere all other factors are equal, including additive vessel volume andtotal additive released in a 300-hour period. Only the inlet tubediameter is adjusted to achieve the correct total additive release. Thefirst graph in FIG. 5 shows how the flowrate is constant for the case ofa vessel that lacks an outlet capillary (since inlet pressure isconstant and viscosity in the inlet tube is constant). When a capillarytube is added to outlet of the container, the initial flowrate isreduced—but the final flowrate has increased almost three-fold due todeclining viscosity.

The graph illustrated in FIG. 6 shows the “active ingredient” oradditive injection rate for these same two cases. When the containerdoes not include a capillary tube outlet, an exponential decay (about80% decrease in this case) in the release rate of the additive isanticipated. When the container contains a capillary tube outlet, theinjection rate curve is significantly flattened (˜50% decrease in therelease rate of the additive) due to the rising flowrate offsetting thedecreasing additive concentration of the diluted vessel mixture. Forboth cases, the total amount of additive released in the 300-hour timeperiod is about equal. However, the case where the container includes acapillary outlet tube provides a more constant release rate over time.This can translate into better protection for the fuel system.

In addition, the rate that liquid enters into container 24 can bevaried. Increasing the pressure differential between entrance port 42and exit port 44 will induce a more rapid in-flow and escape of theliquid and additive mixture from the interior region 40 of container 24.Extending end 49 of capillary tube 48 closer to inlet 18 can increasethe dynamic pressure. Similarly, terminating end 45 of capillary tube 54in an area at lower pressure such as the area proximate to exitingregion 30 can decrease the dynamic fluid pressure at exit port 44.

In another embodiment, varying the configuration and/or size ofcapillary tube 48 and/or capillary tube 54 can vary the pressuredifference between the fluid entering and exiting container 24. Forexample, the diameter of one or both of capillary tubes 48 and 54 can bevaried.

Conversely, placing entrance port 42 and exit port 44 such that therelative pressure differential between the two is small provides for alow flow rate through container 24.

FIG. 7 is a partial view in full section of an alternative embodiment offilter assembly 70 in accordance with the present invention. Filterassembly 70 is formed similarly to filter assembly 10. Consequently,like reference numbers will be used to denote like components.

Filter assembly 70 includes an outer casing 12 defining an interiorchamber 14. A filter element 22 and container 72 are provided in theinterior chamber. Container 72 provides a reservoir for a liquid fueladditive 74. Container 72 includes an exterior wall 76, an entrance port78, and an exit port 80. In the illustrated embodiment, entrance port 78is provided substantially as has been described for entrance port 42 andcan include capillary tube 82. Opening 84 defines exit port 80. Opening84 can be provided as a substantially small diameter opening or acapillary-sized opening. Opening 84 provides direct fluid communicationbetween interior chamber 14 and interior region 73. In one embodiment,opening 84 can open directly into entering region 28 by locating opening84 in a portion of exterior wall adjacent entering region 28, such as aposition diametrically opposite that of capillary tube 82.Alternatively, opening 84 can open directly into exiting region 30 bylocating opening 84 adjacent the exiting region.

FIG. 8 is a partial view with sections broken away of yet anotherembodiment of filter assembly 90 in accordance with the presentinvention. Filter assembly 90 is provided similarly as filter assembly70 and filter assembly 10. Consequently, like reference numbers will beused to denote like components. Filter assembly 90 includes container 92positioned in interior chamber 14. Container 92 includes exterior wall94 defining interior region 96. Entrance port 98 and exit port 100extend through exterior wall 94. Entrance port 98 can be providedsubstantially as described above for entrance port 42 includingcapillary tube 48 and/or entrance port 78 (and capillary tube 82), andexit port 100 can be provided substantially as has been described forexit port 44 including capillary tube 54 and/or exit port 80.

Container 92 also includes one or more interior partitions 102 defininga fluid pathway or channel 104 coursing through the interior region 96.

FIG. 9 is a sectional view of the container illustrated in FIG. 8 takenalong section line 9—9. It can be seen in the illustration thatcontainer 92 contains a partition 102 provided substantially as a spiralwall that defines a curving pathway 104 coursing through interior region96. In a preferred embodiment, partition 102 is provided as a solidportion or wall portion extending the full depth of container 92, i.e.,from the upper surface 110, FIG. 8, to the lower surface 112. In otherembodiments, partition 102 need not extend the full depth of container92 but may be attached to either upper surface 110 or lower surface 112or even as an unattached insert within the interior of container 92. Instill other embodiments, partition 102 need not be a solid wall or animperforate structure but can include openings therethrough.

In the illustrated embodiment, the liquid enters through port 98 andmixes with the liquid additive that is contained within container 92.Consequently, the liquid and additive mixture must course its waythrough the channel 104 defined by partition 102 before the mixture canexit through port 100.

FIG. 10 is a cross-sectional view of another embodiment of a filterassembly 114 in accordance with the present invention. Filter assembly114 is configured similar to filter assemblies 90, 70, and 10;consequently, the same reference numbers will be used to refer to thesame components. Filter assembly 114 includes a container 115 definingan interior region 40 for an additive.

Container 115 includes a first capillary tube 116 defining an inlet andan outlet 122 that provides an opening directly downstream (or thefiltered side) of the filter element. Outlet 122 includes a capillarytube 123 extending upwardly through a second reservoir 127.Consequently, capillary tube 123 can provide a dam to inhibitinadvertent introduction of a secondary additive from the secondcontainer 127 into the container 115. In one embodiment, capillary tube123 is molded directly into the upper wall portion 129 of the firstcontainer 115.

Referring additionally to FIG. 11, it can be seen that the firstcapillary tube 116 is located proximate to the internal wall portion 118of container 115. In this embodiment, outlet 122 is centrally located inthe upper wall portion 129, FIG. 10, of container 115 and thereforeradially spaced from first capillary tube 116.

FIGS. 12 and 13 illustrate one embodiment of a replaceable cartridge 126for use in the present invention. Replaceable cartridge 126 can beconfigured substantially as has been described for containers 115, 92,72, and/or 24. Consequently, the same reference numbers will be used todenote like components. Replaceable cartridge 126 includes an exteriorwall 34 having an entrance port 42 and an exit port 44. Replaceablecartridge 126 provides the added advantage in that it can be readilyplaced in existing filters and/or replaced when the additive containedin the interior chamber has been exhausted. In the illustratedembodiment, cartridge 126 does not include any inserts to direct fluidflow therethrough. However, it will be understood that any of theinserts described above can be included inside container 126 as desired.Such assemblies are intended to be included within the scope of thepresent invention.

FIG. 14 is a cross-sectional view of yet another embodiment of a filterassembly 130 prepared in accordance with the present invention. Filterassembly 130 is configured substantially as has been described forfilter assemblies 10, 70, and 90. Consequently, the same referencenumbers will be used to denote like components. Filter assembly 130includes container 134 axially spaced from a filter element 132 ininterior chamber 133. In this embodiment, it can be observed thatcontainer 134 can be configured substantially as described above for anyof containers 24, 72, 92, and 126. Container 134 can be a removablecartridge and/or include flow directing channels if desired. Container134 can be removed from the interior region by separating lower housing138 from an upper housing or nut plate 140. After lower housing 138 hasbeen separated from upper housing 140, either one or both of filterelement 132 and/or container 134 can be replaced and/or refurbished. Forexample, container 134 can be replaced with a new container or cartridgefilled with an additive. Alternatively, existing container 134 berefilled with a fresh charge of an additive.

Capillary tube 136 defines an inlet into the interior region 138 ofcontainer 134. It can be observed from the illustration that capillarytube 136 extends substantially the full length of filter element 132.However, capillary tube 136 only extends a short distance through theupper wall portion inside container 134. The terminus of capillary tube136 can include one or more of a seal (such as a seal soluble in theliquid flowing through the filter), a filter element, or a porous orother mesh covering as discussed above.

Capillary tube 140 defines an outlet port 142 from container 134.Capillary tube 140 extends up into the exiting region 30. Optionally,capillary tube 140 can also include one or more of a seal, such as asoluble seal, a filter element or a porous or other mesh covering 141over either terminus. The opposite end of capillary tube 140 extendsnearly to the lower wall portion or bottom of container 134.

In this embodiment, the liquid enters container 134 through capillarytube 140. Since the liquid typically is less dense than the additive incontainer 134, the liquid will first layer on top of the additive andforce substantially pure additive out through capillary tube 140 andinto the portion of the liquid flowing through the exiting region 30.

In the preferred embodiment, the difference in liquid density and theadditive density can be utilized to achieve a more uniform release rateover time. Since the liquid is less dense than the liquid additive, theliquid tends to “float” on the additive phase and the inlet tube istruncated near the top of the additive vessel, whereas the outletcapillary extends to near the bottom of the vessel. During operation, asthe liquid enters the inlet vessel and “floats” and remains (withexception of the slow diffusion between phases) on the top of thevessel, displacing pure additive and pushing it out the outlet tube innearly full-concentration yielding a very steady injection of activeingredient into system.

FIG. 15 is still yet another embodiment of a filter assembly 150. Filterassembly 150 can be provided substantially as has been described forfilter assemblies 10, 70, 90 and 130. Consequently, the same referencenumbers will be used to denote like components. Filter assembly 150includes a container 152 in an interior chamber 154. Capillary tube 156provides an inlet into the interior region 158 of container 152. In thisembodiment, capillary tube 156 extends in a direction parallel to andsubstantially along the entire length of filter element 22. Upper endcap159, shown in an enlarged view in FIG. 16, includes a shroud 160 thatextends downwardly and in a radially direction toward the upper end 162of capillary tube 156.

In this embodiment, the endcap shroud 160 cooperates with filter shell164 to constrict the flow and hence increase the velocity in closeproximity to entrance of capillary tube 158. This in turn increases thedynamic fluid pressure at end 162. Consequently, the pressure differencebetween the entrance and exit from container 152 is greater than wouldbe observed if the fuel were not constricted between filter endcapshroud and shell.

FIG. 17 is a cross-sectional view of yet another embodiment of a filterassembly 180 in accordance with the present invention. Filter assembly180 includes some of the same or similar components as discussed forfilter assembly 10; therefore, the same reference numbers will be usedfor the same components. Filter assembly 180 includes an outer casing orhousing 182 that defines an interior chamber 184. A filter element 22and a vessel or container 186 are positioned in the interior chamber.Filter element 22 can partition the interior chamber 184 into a fluidentering region 188 and a fluid exiting region 190. Additionally, filterassembly 180 can include a separable lower bowl 192 for water collectionwith a drain valve 193 to expel the collected water.

Container 186 includes an exterior wall 194 that defines an interiorregion 196. An additive 198 such as has been described above is disposedin interior region 196. A first, inlet 200 allows fluid to flow intointerior region 196. An outlet 202 allows the additive and/or a mixtureof the fluid and additive to flow out of interior region 196. In theillustrated embodiment, it can be observed that inlet 200 allows fluidfrom the fluid entering region 188 to flow into interior region 196while the outlet 202 allows the additive and/or fluid additive mixtureto flow out of the interior region and into the fluid exiting region190. Container 186 can be charged with the liquid additive through aclosable or sealable opening 191 prior to final assembly.

Inlet 200 is surrounded by a short, cylindrical boss covered by a filterelement or filter media 204. In this particular embodiment, inlet 200need not be a capillary tube and need not extend into the interiorregion 196. Rather inlet 200 is configured as a short, cylindricalopening having a diameter of approximately between 1 mm and about 10 mm.Filter media 204 can be formed of the same material as used for thefilter element 22 or a different material as desired. The filter media204 can be supported by cross ribs extending across the opening. Thefilter media 204 can be formed of a material or configured and/or sizedto minimize the pressure drop across the inlet 200. In one embodiment,the fluid face velocity (and hence pressure drop, since restriction toflow across porous media is proportional to the velocity of flow)through inlet 200 is about 50% of that through filter element 22; morepreferably, less than about 25%; and still more preferably less thanabout 10% lower than that observed to flow through filter element 22.

As used herein the term fluid face velocity is defined as the “approachvelocity” of a liquid flowing normal to the surface of the filtermaterial according to Equation 3:FV=volumetric flowrate/area [m/s]  (3)where FV is the fluid face velocity and volumetric flowrate is thevolumetric flowrate of the fluid approaching the filter material.

Additionally, if desired, filter element 204 can be covered or sealedwith a fluid soluble seal 206. Seal 206 can be provided to inhibitaccidental leakage of the additive 198 during storage and shippingand/or prevent contact of the additive to air prior to use.

Outlet 202 in this illustration includes a capillary tube 210. Capillarytube 210 can operate to control the rate of release of the additive (ora mixture of fluid and additive) out of container 186. Capillary tube210 extends from the interior region 196 through outlet 202. An exteriorportion 212 of capillary tube 210 is surrounded by a support structure214. In the illustrated embodiment, support structure 214 is provided asa conical boss 216 which provides support and minimizes the risk ofdamage to the exterior portion 212 of capillary tube 210. To furthersupport and reduce the risk of plugging during assembly, the terminalend of capillary tube 210 be recessed in conical boss 216. In oneembodiment, support structure 214 includes a plurality of radiallyextending ribs 217, which can extend beyond the terminal end ofcapillary tube 210. While boss 216 is illustrated as a conical or afrustum conical configuration other configurations are contemplated.Boss 216 bears against a seal 218 about an inner portion of end cap 220,which supports filter element 22. Engagement between boss 216 and seal218 provides a fluid-tight seal to prevent fluid flowing though theassembly from bypassing both filter element 22 and container 186. In theillustrated embodiment, capillary 210 and boss 216 are centrally locatedin the top wall portion of container 186.

Capillary tube 210 extends into interior region 196. In preferredembodiments, capillary tube 210 extends to a position in close proximityto the bottom wall portion 222 of container 186. The length of capillarytube 210 can be varied as desired to control or limit the additiverelease rate. The capillary tube 210 defines a flow path for theadditive and/or additive/fluid mixture in container 186. In oneembodiment, capillary tube defines a flow path that has a length greaterthan the depth of container 186, measured from the upper wall portion tothe lower wall portion.

The present embodiment of a filter assembly 180 provides distinctadvantages. The illustrated embodiment provides particular advantagesfor additives, which are denser than the fluid flowing through theassembly. In the illustrated embodiment, the inlet 200 is provided as acylindrical opening. This reduces the variation in the additive releaserate of flow since the majority of the pressure gradient developedbetween the inlet 200 and the outlet 202 is across the capillary tube210. Thus, the capillary tube configuration can be tailored to controlthe release rate of the additive. This can include varying the lengthand/or diameter of capillary tube 210 to fine tune the release rate ofthe additive into the fluid. Increasing the diameter of capillary tube210 increases the rate of release by a factor proportional to the(capillary internal diameter)⁴. Increasing the length of capillary tube210 decreases the rate of release by a factor inversely proportional tothe capillary length.

Additionally typically during use the filter media retains particlesfrom the fluid. Eventually near the end of the filter assembly's usefullife span, the filter media may become sufficiently clogged with theparticles that the pressure differential between the entering region 188and the exiting region 190 significantly increases. This greaterpressure differential forces any remaining liquid additive out ofcontainer 186 into the fluid where it can provide a benefit to the fluidrather than being disposed of when the filter assembly is replaced.

Referring additionally to FIG. 18 which illustrates a cross-sectionalview of another embodiment of a container 230. In container 230,capillary tube 232 is illustrated as extending all the way to the bottomwall portion 222 terminating in a spiral winding 234. This, in effect,lengthens capillary tube 232 to accommodate a greater pressuredifferential while still maintaining the desired flowrate of theadditive out of the interior region 196. It should be understood thatthe spiral winding 234 can extend or spiral in any direction. However,it is preferred that the end of capillary 232 be positioned proximate tothe bottom wall portion 222. As noted above, typically the liquidadditive is denser than the fluid flowing through the assembly.Consequently, positioning the end of the capillary tube near the bottomwall of container 230 ensures that all of the additive is released intothe fluid.

FIG. 19 illustrates a perspective view of a container 186 for use infilter assembly 180. In this embodiment, container 186 includes areservoir 240 formed in the upper wall portion 242. A pre-chargeadditive can be deposited in reservoir 240 to be directly added to thefluid in filter assembly 180. This provides an additional “additiveboost” upon initial employment of the filter assembly 180. As discussedabove, the additive pre-charge deposited in reservoir 240 can, ifdesired, also be coated with a fluid soluble seal or seal material suchas a wax for organic fluids or a water-soluble polymer for aqueous basedfluid.

FIG. 20 is a partial view, in cross-section of an alternative embodimentof a filter assembly 250. In this embodiment, a container 252 isillustrated which includes a capillary tube 254 extending through acylindrical boss 256. An O-ring seal 258 on top of boss 256 sealsagainst the lower end cap 220 to ensure a fluid-tight seal and preventany fluid from bypassing both filter element 22 and container 252.

FIG. 21 is an exploded, perspective view of the lower portion ofcontainer 186 and lower bowl 192. It can be seen from this embodimentthat container 186 includes a plurality of concentric ribs 264positioned about the exterior wall 194. This allows a space or gapbetween the exterior wall 194 of container 186 and housing 182 to allowany water to drain down into the lower bowl 192. The water can thendrain through channels 266 into bowl 192. Bowl 192 can include athreaded stud 268, which can be threadedly engaged with a threadedrecess 270 in the lower portion of container 186. In preferredembodiments, lower bowl 192 can be provided with a drain relief valve193. Additionally, lower bowl 192 can be provided with an electronicsensor to sense moisture contained therein or can be made of a clearmaterial through which the water can be visually observed.

Filter assembly 180 provides additional advantages in that it can beused with vacuum side filter applications. In vacuum side applicationslittle fluid is present in the entrance region 188 between filterelement 22 and shell wall 182—the fluid at that location is mainlyvapor. In a vacuum application, the liquid is generally confined to azone approximately beneath endcap 220 and in the fluid exiting region190. Because the opening 200 is below the endcap 220, the liquid ispresent to flow into container 186 through the inlet 200.

The present invention provides distinct advantages to current deliverysystems. The use of a liquid additive in the container allows themaximum amount of an additive to be included within a filter assemblybecause the liquid additive can completely fill the internal volume ofthe container where as solid additives do not. Furthermore, byharnessing the pressure gradient generated within a filter assembly inuse, the rate of addition of the additive is much more independent ofvibration variation that may occur during use. However, the rate ofrelease of the additive as noted above can be adjustable by varying thelength and/or diameters of the capillary tubes leading into and out ofthe container holding the fuel additive.

The present invention also provides a method of adding beneficialadditives to the liquid only with the liquid flowing through the filter.When the liquid is not flowing through the filter, diffusion of anyadditive out of the container has been measured to be negligible becauseof the extremely low molecular diffusion rate. The molecular diffusionrate is described by the binary diffusion coefficient, which in theabove-described embodiments with the liquid/additive is on the order of2e⁻⁶ cm²/s between the additive and the liquid phases, and the dynamicfluid pressure gradient is zero when there is no flow so convectivetransfer is also eliminated.

The present invention also contemplates modifications as would occur tothose skilled in the art. It is also contemplated that the devices andprocesses embodied in the present invention can be altered, rearranged,substituted, combined, or added to other processes as would occur tothose skilled in the art without departing from the spirit of thepresent invention. All patents and patent applications cited in thisspecification are herein incorporated by reference as if each individualpatent or patent application was specifically and individually indicatedto be incorporated by reference and set forth in its entirety herein.

Any reference to specific directions, for example, references to up,upper, top, bottom, down, lower, on top of, below, and the like, is tobe understood for illustrative purposes only or to better identify ordistinguish various components from one another. These references arenot to be construed as limiting in any manner to the devices, methods,and/or operations as described herein.

Unless specifically identified to the contrary, all terms used hereinare used to include their normal and customary meaning.

Further, while various embodiments of filter assemblies having specificcomponents and structures are described and/or illustrated in theFigures herein, it is to be understood that any selected embodiment of afilter assembly can include one or more of the specific componentsand/or structures described for other embodiments where possible.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is considered to beillustrative and not restrictive in character. It is understood thatonly the preferred embodiments have been shown and described and thatall changes and modifications that come within the spirit of theinvention are desired to be protected.

1. A filter assembly comprising: a housing defining an interior chamber;a filter element disposed within the housing and partitioning theinterior chamber into an inlet region and a filtered region; a containerpositioned within the housing defining a reservoir, the containerincluding a first opening providing fluid communication between theinlet region and the reservoir and a second opening providing fluidcommunication between the filtered region and the reservoir, wherein thesecond opening includes a capillary tube, and wherein the containerincludes a boss extending into the filtered region and supporting thecapillary tube.
 2. The filter assembly of claim 1 wherein the capillarytube is recessed in the boss.
 3. The filter assembly of claim 1 whereinthe filter element is supported by an end cap and a sealing member ispositioned between the boss and the end cap.
 4. The filter assembly ofclaim 3 wherein the sealing member is a compression seal or a radialseal.
 5. A filter assembly comprising: a housing defining an interiorchamber; a filter element disposed within the housing and partitioningthe interior chamber into an inlet region and a filtered region; acontainer positioned within the housing defining a reservoir, thecontainer including a first opening providing fluid communicationbetween the inlet region and the reservoir and a second openingproviding fluid communication between the filtered region and thereservoir, wherein the second opening includes a capillary tube, whereinthe capillary tube extends inside the container, and wherein thecontainer has an upper wall portion and a lower wall portion defining adepth therebetween, and the capillary tube defines a flow path thereinhaving a length greater than the depth of the container.
 6. The filterassembly of claim 5 wherein the capillary tube terminates inside thecontainer in a spiral wound tube.
 7. A filter assembly for filtering afluid, said filter assembly comprising: a housing defining an interiorchamber, the housing including a nut plate having an inlet and an outletfor the fluid; a filter element permeable to the fluid and disposedwithin the housing; a container positioned within the housing, thecontainer defining a reservoir configured for receipt of a liquidadditive, the container including a first opening allowing fluidentering from the inlet to flow into the reservoir and a second openingallowing a liquid additive deposited within the reservoir to flow to theoutlet, wherein said second opening is constricted relative to the firstopening to control the fluid flow into the container, wherein the secondopening includes a capillary tube, and wherein the container includes aboss supporting the capillary tube.
 8. The filter assembly of claim 7wherein the capillary tube is recessed in the boss.
 9. The filterassembly of claim 8 wherein the filter element is supported by an endcap and a sealing member is positioned between the boss and the end cap.10. The filter assembly of claim 8 wherein the container has an upperwall portion and a lower wall portion defining a depth therebetween, andthe capillary tube defines a flow path therein having a length greaterthan the depth of the container.
 11. The filter assembly of claim 10wherein the capillary tube terminates inside the container in a spiralwound tube.